Process for the production of olefinically unsaturated hydrocarbons

ABSTRACT

Hydrocarbon feedstock containing petroleum residuum is catalytically cracked in a heavy oil cracking unit to produce a naphtha feed suitable for processing by steam pyrolysis to olefins. By the process integration disclosed, internal gas compression energy requirements for olefins recovery are furnished by steam generated in the heavy oil cracking unit.

O United States Patent I I I 1 3,862,898

Boyd et al. Jan. 28, 1975 PROCESS FOR THE PRODUCTION OF mithiuii ampeeta glYdEFlNlCALLY UNSATURATED 3.l80,904 4/l965 Fischer et al. 260/683DROCARBONS 3.40l l24 9/1968 Gouldcn I I 252/4I7 [75] Inventors; HaroldB, Boyd; James R, Lambrix, 3.532.620 l0/l970 Asmus et al. 208/] I3 bmhFOREIGN PATENTS OR APPLICATIONS 1 Assigneel Pullman Incorporated,Chicago 935.681 9/]963 Great Britain 260/683 [22] Filed; July 30, 1973 LI E 0 Primary xuminerDe bert amz [2]] Appl' 383620 Assistant Examiner-C.E. Spresser [52] US. Cl 208/73, 208/72, 208/77, 57] ABSTRACT 260/683 RHydrocarbon feedstock contaming petroleum resid- [51] Int Cl Clog 37/04uum is catalytically cracked in a heavy oil cracking [58] Fie'ld I 13 H0unit to produce a naphtha feed suitable for processing "5 5 4 by steampyrolysis to olcfins. By the process integration disclosed, internal gascompression energy re- [56] References Cited quirements for olefinsrecovery are furnished by steam UNITED STATES PATENTS generated in theheavy oil cracking unit.

2 42l,6l5 6/!947 Shepardson 208/73 ll Claims 3 Drawing Figures PROCESSFOR THE PRODUCTION OF OLEFINICALLY UNSATURATED IIYDROCARBONS Thisinvention relates to the integration of fluid catalytic cracking ofheavy hydrocarbon oils containing petroleum residuum and thermalpyrolysis of hydrocarbons to produce olefmically unsaturatedhydrocarbons such as ethylene and propylene.

l-leretofore, it has been known to convert naphtha, ethane, or porpanefeedstocks to olefins by themal pyrolysis with steam. Conventionalprocesses are broadly disclosed in the Nov. 13, 1965 issue of ChemicalWeek. pasesl ril- It has also been known to fractionate a crudepetroleum oil and pyrolytically convert selected distillate fractions toolefins according to US. Pat. No. 3,409,540. In this process, however,residuum from such fractionation is diverted to fuel oil use and noattempt is made to derive pyrolysis feed from it. Moreover, in order tominixmize residum production, a heavy gas oil cut form the fractionatoris hydrocracked and certain separation products from hydrocracking arethereby rendered suitable for pyrolysis feed.

In a related process disclosed in US. Pat. No.

3,617,495, residuum from crued oil distillation is coked and cokernaphtha so produced is made suitable for pyrolysis feed byhydrotreatment. In this process, however, relatively large amounts offuel oil are produced from the distillation zone and from the coker. Thecoke and fuel oil resulting from these operations cannot be readilyutilized in ethylene production.

It is an object of this invention to provide a more efficient and lessexpensive process for the manufacture of olefins and aromatic compounds.Another object of the invention is to integrate catalytic cracking ofheavy hydrocarbons with thermal pyrolysis of light hydrocarbon feeds toefficiently produce olefins and aromatic compounds. Another object ofthe invention is to provide a process for olefins production fromresidual feedstocks. Yet another object of this invention is to provideinternal compression energy requirments for recovery of olefins producedby thermal pyrolysis from components of crude petroleum oil that areunsuitable pyrolysis feeds. Further objects and advantages of theinvention will be apparent from the drawings and the followingdescription.

According to the invention, a heavy hydrocarbon containing petroleumresiduum is converted to cracked products including naphtha in a heavyoil cracking unit having a fluid catalytic cracking zone and a catalystregenreration zone. The naphtha is passed to a noncatalytic thermalpyrolysis zone and converted to thermally cracked effluent containinglarge quantities of olefins having from 2 to 4 carbon atoms. The olefinsare recovered in a known manner by process gas compression andrefrigeration. In addition, high pressure steam is produced in theregeneration zone of the heavy oil cracking unit and the steam soproduced is utilized in olefins recovery. FIG. 1 outlines theintergration of residuum catalytic cracking in a heavy oil cracking(HOC) unit with thermal pyrolysis of the resulting cracked naphtha fromthe HOC unit to produce C -C olefins and the recovery of such olefins byutilization of heat energy derived from the HOC unit.

FIG. 2 is a schematic diagram of a petrochemical refinery and disclosesthe production of C -C 4 olefins and aromatic compounds from crudepetroleum oil wherein a substantial part of the thermal pyrolysis feedis derived from a residue fraction: of the crude oil.

FIG. 3 is a schematic diagram of steam generation and use within thepetrochemical refinery concept of FIG. 2 and discloses a total energyconcept with fulfillment of the entire gas compression energyrequirements of the process through internal process generation of steamwith consequent fuel and power savings. Referring to FIG. 1, ahydrocarbon feedstock containing petroleum residuum is introduced to thecatalytic cracking zone 1 of a heavy oil cracking (HOC) unit. Thefeedstock may be whole crude petroleum oil, topped petroleum crude,residue containing fractions from petroleum refining steps such asvisbreaking, solvent deasphalting, hydrodesulfurization, and vacuumdistillation but is preferably residuum boiling above about 600F thathas been derived from atmospheric distillation of crude petroleum oill.Such crude oil may contain from 0.1 to 8 weight percent sulfur, from 1to 1,000 ppm organometallic compounds such as compounds of vanadium andnickel, and asphaltenes ranging from about 0.1 to about 20 volumepercent. Wher asphaltene content is high, the residue fraction mayundergo deasphalting or deasphaltening prior to further processing.

The heavy oil cracking (HOC) unit comprises a fluid catalytic crackingzone 1 and a catalyst regeneration zone 2. Fluidized cracking catalystcirculating between the two zones may be of conventional type such asactivated clay, silica-alumina, silica-zirconia, and aluminaboria,however, natural and synthetic zeolitic catalysts, particularly of themolecular sieve, matrix type having an average particle size range offrom about 40 to about 100 microns, are preferred cracking catalysts.

The catalytic cracking zone 1 is. preferably a transfer line reactor andis most preferably a riser reactor of the type described in US. Pat. No.3,607,127. The riser type unit is more fully depicted in FIG. 2 of thedrawmgs.

In operation of the HOC unit, residue containing hydrocarbon feedstockis fed to the lower part of the riser reactor at a temperature of fromabout 150F to about 750F and is admixed with the cracking catalyst inthe presence of fluidizing steam. Typical cracking conditions include atemperature range: from about 850F to about 1,200F, pressure from about10 psig. to about 50 psig., catalyst to oil ratio of from about 3:1 to15:1, and space velocity of from about 0.5 to 1,000. Normally from 50 topercent of the cracking reaction takes place in the riser reactor withthe remainder occurring in the disengaging and stripping zones locatedgenerally in the upper part of the heavy oil cracking unit. Crackedeffluent including a cracked naphtha fraction leaving the riser reactordisengages from catalyst in the upper part of the HOC unit and exitsthrough a series of cyclone separators that. return entrained catalystto a fluid bed regeneration zone belowthe disengaging zone. Severecracking conditions are employed in order to maximize conversion of thefeedstock to naphtha boiling range hydrocarbons for thermal pyrolysisfeed. Generally, at least 65 volume percent and most preferably 80 topercent of the feed is cracked to light hydrocarbons boiling in thenaphtha range, gases including hydrogen, cycle oil, and coke.

Following disengagement from cracked effluent, catalyst contaminatedwith coke and occluded hydrocarbons passes downwardly through astripping zone. The

stripping zone is fitted with suitable baffling and steam sparging meansto strip occluded cracked effluent which passes over head while catalystcoated with coke and some non-volatile hydrocarbons passes downwardlyinto regeneration zone 2 located in the lower part of the I-IOC unit.

In the regeneration zone catalyst is contacted with an oxygen-containinggas, preferably air, furnished by a regenerator air blower or compressor(see reference numeral 46 in FIG. 2). Air furnished by this blower willnormally be at a pressure of from about 20 psia. to about 70 psia. anddelivered at a rate of from about I 1 pounds to about 13 pounds perpound of coke burned from the catalyst. The air delivery rate is variedin order to maintain regeneration zone temperatures of from about l,000Fto about l,400F and at which temperature materials coated on thecatalyst are burned off to desired levels of residual coke onregenerated catalyst. Such levels will generally be from about 0.05 toabout 0.4 weight percent, preferably from about 0.05 to about 0.15weight percent. Following regeneration, catalyst is returned to theriser reactor.

In view of the generally high carbon content of residue fractionsprocessed by the l-IOC unit and the formation of additional carbon orcoke during cracking, coke deposits on the cracking catalyst willnormally be heavy. Due to combustion of this carbon, a substantialamount of heat is evolved during regeneration of cracking catalyst whichis recovered through indirect heat exchange as high pressure steam,preferably at a pressure of from about 1,000 psia. to about 2,000 psia.by introducing boiler feed water to steam coils or tubes located withinthe regeneration zone (see reference numerals 50, 51, and 52 in FIG. 2).In most instances the steam coils will be interconnected to a suitableflash drum and auxiliary equipment (not shown).

High pressure steam so produced is utilized in expansion turbine drivesshown generally be reference numeral 3 employed in gas compressionrequired for olefins recovery. In an integrated petrochemical refineryas shown in FIG. 2, later described, the quantity of high pressure steamfrom the regeneration zone of the HOC unit is sufficient to provide atleast a major part of the gas compression energy requirements of theprocess and will generally provide about two-thirds of this requirementin terms of the weight flow rate of steam generated and expanded incompressor turbine drives. The term gas compression energy is intendedto mean the total energy expended in compressing pyrolysis effluent gasto the pressure required for olefins recovery in addition to terefrigeration compression required for chilling pyrolysis effluent inorder to perform product separations by fractionation. Generally, thecompression energy required for these purposes will be about equallydivided between process gas compression and refrigeration compression.High pressure steam may drive turbo-generators and indirectly providesuch gas compression energy requirements through electromechanicalmeans, however, direct steam turbine drives to the compressors willgenerally be preferred.

A major part of the steam expanded through the turbines is condensed andrecycled through a boiler feed water system. Preferably, a portion ofthis steam is further expanded to reduced pressure ranging from about Ipsia. to about 200 pisa. for use as steam diluent of hydrocarbon feed tothermal pyrolysis zone 4.

A cracked naphtha fraction separated from catalytically cracked effluentleaving the HOC until may be passed directly to thermal pyrolysis zone5, however, the fraction will normally contain 'olefinic materials thattend to form coke and to polymerize excessively when subjected topyrolytic conversion. Preferably the cracked naphtha fraction ishydrotreated, as will be later described. The cracked naphtha fractionis then admixed with diluent steam from the expansion turbines andintroduced to thermal pyrolysis zone 5 which will be subsequentlydiscussed in connection with FIG. 2.

Thermally cracked effluent from the pyrolysis zone is then cooled andpassed to process gas compression zone 6 and pressurized to from about400 psia. to about 650 psia. to facilitate fractionation of products.Separations of hydrogen, fuel gases, ethane, propane, mixed C compounds,and products including ethylene and propylene are than performed inproduct recovery zone 7 by known chilling and separation steps A typicalseparations process is described in the Nov. 13, 1965 issue of ChemicalWeek," 77-80.

In a preferred embodiment the integrated process is carried outaccording to the following example- Referring now to FIG. 2, 690,000lb./hr. of desalted whole petroleum crude oil contaihin g 26weightpercent sulfur is introduced through line 25 to thermal distillationzone 26. A gaseous overhead fraction comprising predominantly C and Cparaffmic hydrocarbons is removed through line 27. A straight-runnaphtha fraction boiling between about F and about 450F is removed fromthe distillation zone through lines 28 and 34 and passed to thermalpyrolysis zone 35. A light gas oil fraction boiling in the range fromabout 300F to about 650F is also removed from the distillation zone andpassed through lines 29 and 34 to pyrolysis zone 35. A heavy gas oilfraction boiling in the range from about 550F to about l,000F is removedfrom a lower section of the distillation zone through line 30 andhydrodesulfurized in zone 31 with hydrogen introduced through line 32.The hydrodesulfurizer may utilize cobalt-molybdenum or alumina catalystand is operated at temperatures ranging from about 550F to 750F andpressure ranging from about 200 psia. to about 600 psia. Desulfurizedgas oil is then passed to the thermal pyrolysis zone through lines 33and 34. If desired, portions of the naphtha or gas oil fractions may bediverted to other uses, however, in an integrated petrochemical refineryof the type described herein, it is preferred to pass these fractions tothe thermal pyrolysis zone in order to maximize olefins and aromatichydrocarbons production.

From the bottom of thermal distillation zone 26, 365,000 lb./ hr, of apetroleum residuum fraction boiling above about 600F is removed throughline 36 and passed through line 37 to catalytic cracking zone 38 ofheavy oil cracking unit 39. The catalytic cracking zone in FIG. 2 isillustrated as a riser reactor.

Alternately, all or part of the residue fraction from thermaldistillation zone 26 may be passed through a solvent de asphalting zone,for example a propane deasphalting unit, to obtain a deasphalted oilwhich is subsequently charged to the HOC unit. This step will generallynot be used when asphaltene and metals content of the residue fractionis not excessively high.

The residuum fraction is fed to the lower part of riser 38 to atemperature of from about l50F to about 750F and is admixed withcirculating, regenerated cracking catalyst and with fluidizing steamintroduced from line 40 at about 100 psia. Cracked effluent including acracked naphtha fraction laeaving riser 38 disengages from the catalystin disengaging zone 41 and passes upwardly through cyclones (not shown)for recovery through line 43.

Catalyst with coke and occluded hydrocarbons deposited thereon passesdownwardly through the disengaging zone to stripping zone 42 for removalof occluded hydrocarbons which pass overhead with the cracked effluent.Stripped catalyst then passes to regeneration zone 44 where coke andnon-volatile hydrocarbonaceous materials are burned from the catalystwith air introduced through line 45 from regenerator air blower 46. Fluegases containing carbon monoxide from the regeneration step leave zone44 through line 47 for further use and treatment.

Heat produced during regeneration is removed by passing boiler feedwater through line 50 to coils 51 located within the regeneration zoneand thereby producing steam by indirect heat exchange at a high pressureof about 1,500 psia. which is removed at a rate of 650,000 llb./hr.through line 52.

Cracked effluent removed from the HOC unit through line 43 is introducedto cracker fractionator 53 at a temperature of about l,000F and pressureof about psia. A volatitle overhead stream comprising hydrogen andparaffinic hydrocarbons lighter than C, is removed from the crackerfractionator through line 54. ln conventional refinery operations, C andlighter materials would be used as plant fuel or compressed and divertedto other process facilities. Here, the stream is combined with overheadin line 27 from thermal distillation zone 26 and integrated into olefinsproduction as later described.

Decant oil is removed from the bottom of a cracker fractionator 53through line 55 and is preferably passed to catalytic cracking zone 38of the HOC unit through line 37. Alternately, all or a part of this oilmay be diverted to other uses, for example, carbon black produc tion orauxiliary fuel. A cycle oil suitable for further processing tocommercial fuel oil is removed by way of line 56.

The principal product of the HOC unit, a cracked naphtha fractionboiling between about 85F and about 450F is removed from the crackerfractionator through line 57 at the rate of 127,000 lb./hr. and passedto hydrotreating zone 58 for olefins saturation and desulfurization inthe presence of a catalyst with hydrogen introduced to the hydrotreatingzone. Additionally, 92,000 lb./hr. of pyrolysis gasoline from downstreamprocess sources later described is passed to hydrotreatment zone 58 forsimilar processing. Hydrotreating will serve to prepare the feed forpyrolytic conversion by saturating olefms, partially saturating aromaticcompounds, and by removing sulfur contained in the fraction byhydrodesulfurization. A substantial part of the hydrogen required inhydrotreating may be obtained from the hydrogen produced in the HOC unitand later recovered in the product separation zone.

Hydrotreating is generally performed in one or more stages attemperatures ranging from about 450F to about 800F and pressures fromabout 100 psia. to 1,500 psia. Preferred hydrotreating catalystscomprise one or more hydrogeneration metals supported on a suitablecarrier material. Oxides or sulfides of molybdenum, tungsten, cobalt,nickel, and iron supported on such supports as alumina andsilica-alumina are used. The most preferred catalysts are cobaltmolybdate or alumina and nickel molybdate on alumina. The catalyst canbe employed in the form of a fixed bed or a fluidized bed. Liquid phaseor mixed phase conditions can be used. Space velocities are from about 1to about 15 volumes of feed per volume of catalyst per hour and hydrogenaddition rates are from about 50 to about 2,000 SCF/bbl. A number ofhydrogen treating processes of varying degrees of severity are disclosedin Hydrocarbon Processing, September 1972, pages -184.

A hydrotreated naphtha fraction containing predominantely C paraffinichydrocarbons is recovered from the hydrotreating zone and passed throughline 59 to thermal pyrolysis zone 35 at the rate of 35,000 lb./hr.

A hydrocarbon stream containing naphtha and aromatic compounds is alsoseparated in hydrotreating zone 58 and passed through line 60 to anaromatics extraction and separation zone 61 which may typically utilizesolvent extraction by, for example, ethylene glycol, furfural, ordimethyl formamide. Proudct separations in extraction zone 61 yields39,000 lb./hr. of benzene, 24,000 lb./hr. oftoluene, and 12,000 ]b./hr.of xylene. 104,000 lb./hr. of paraffiniic raffinate resulting fromaromatics extraction is then passed through lines 62 and 59 to thermalpyrolysis zone 35.

Thermal pyrolysis zone 35 contains pyrolysis furnaces adapted fro steamcracking of hydrocarbons varying from light paraffms to gas oils toproduce C to C olefins. In FIG. 2, the thermal pyrolysis feed steamspreviously described are mixed with 310,000 lb./hr. of diluent steamfrom line 63 at a pressure of about 150 psia. Such steam is obtainedfrom the discharge of gas compressor turbines as later described.Diluent ratios are about 0.6 pounds of steam per pound of naphtha feed,and 0.75 pounds of steam per pound of gas oil feed. It is understoodthat individual furnaces within the thermal pyrolysis zone may varysomewhat in detail design to suit the particular feed streams involved.Typically, a pyrolysis furnace will contain convection heating coils inwhich feed materials are preheated to temperatures as high as l,200F andradiation sections in which preheated feed is converted to olefins inthe presence of diluent steam at temperatures in the range of aboutl,400F to about 2,000f depending on the feedstock used and product mixdesired. Residence time of hydrocarbons in the furnaces is low,generally from about 0.2 seconds to about 2.0 seconds and maybe as lowas 0.01 seconds.

Thermally cracked effluent containing C -C olefins, pyrolysis gasoline,pryrolysis oil, hydrogen, and light paraffms is passed from the thermalpyrolysis zone through line 64 to quench zone 65 where the effluent israpidly cooled to a temperature of from about 600F to about 1,000Fdepending on the pyrolysis feedstock. Boiler feed water is introduced tothe quench zone and passed in indirect heat exchange with the thermallycracked effluent to produce 542,000 lb./hr. of steam at a pressure ofabout 1,500 psia. which is removed through line 66.

Thermally cracked effluent is passed from quench zone 65 through line 67to effluent fractionator 68 where a pyrolysis oil bottoms fraction isremoved and passed to the catalytic cracking zone 38 of the heavy oilcracking unit 39 at the rate of 43,000 lb./hr. through lines 69, 36, and37. An overhead fraction containing the oil-depleted thermally crackedeffluent is recovered from the effluent fractionator through line 70 ata pressure of about 7 psig. and admixed with light hydrocarbonscontained in lines 27 and 54. the combined effluent stream is thenpassed through line 27 to a process gas compression zone 71 wherepressure is increased from 7 psig. to 550 psia. in order to facilitateproduct separations. a pyrolysis gasoline stream containing aromaticcompounds, principally aromatic hydrocarbons such as benzene, toluene,and the xylenes, is separated from combined effluent in the gascompression zone 71 and passed through line 72 to previously describedhydrotreating zone 58.

Following compression and pyrolysis gasoline removal, the combinedeffluent is passed through line 73 to acid gas separation zone 74 forremoval of carbon dioxide and hydrogen sulfide, thence through line 75to drying zone 76, and then through line 77 to chilling zone 78 wherethe effluent stream is cooled by refrigeration supplied fromrefrigeration compressors 79. Hydrogen is removed from chilling zone 78through line 80 at the rate of 7,000 lb./hr. This hydrogen is utilizedin hydrotreating zone 58, hydrodesulfurization zone 31, and may be usedfor desulfurization of fuel oil separated in the cracker fractionactor53.

Chilled pyrolysis effluent is then passed thro igl line 81 Ito productseparation zone 82 where 152,000 lb./hr. of ethylene, 81,000 lb./hr. ofpropylene, and 91,000 lb./hr. of mixed C hydrocarbons are spearated byfractionation and removed as products of the process. Additionally,38,000 lb./hr. of ethane and 14,000 lb./hr. of propane are removed fromthe product recovery zone and recycled via lines 83, 59, 33, and 34 tothermal pyrolysis zone 35. A residual stream of pyrolysis gasoline isalso removed through line 84 and passed to hydrotreating zone 58.

A preferred embodiment of the total energy concept of the inventionfollows.

Referring now to FIG. 3, which illustrates steam integration witholefins production from crude oil, processing zones are those previouslydescribed for FIG. 2, however, many of the interconnecting process lineshave been omitted for clarity.

Steam at a high pressure of about 1,500 psia. is recovered from theregeneration zone 44 of the HOC unit 39 as previously described anddelivered at the rate of 650,000 lb./hr. through line 52 to highpressure steam header designated by reference numeral 85.

Additionally, 542,000 lb./hr. of 1,500 psia. steam is recovered fromquench zone 65 and delivered through line 66 to high pressure steamheader 85.

Since flue gas produced from the oxidation of coke in the HOC unitregeneration zone will normally contain an appreciable amount of carbonmonoxide, it is preferably passed to CO boiler 48 and burned with theaid of a high heat value fuel such as recovered fuel gas to generatehigh pressure steam from boiler feed water. All or part of the steamthus produced may be used in fulfilling the remaining energyrequirements of the process, providing energy required by theregenerator air blower, or exported as a product of the 'process.Accordingly, 650,000 lb./hr. of 1,500 psia. steam is recovered from theCO boiler 48 and delivered through line 49 to high pressure steam header85.

100,000 lb./hr. of the high pressure steam from header 85 is passedthrough line 86 and expanded through regenerator air blower 46. Steamexhausted from turbine 87 is then returned through line 92 to boilerfeed water recovery system 93 where it is condensed, treated andrepressurized for distribution by suitable lines (not shown) to thepreviously described steam generation zones. 1

High pressure steam is similarly passed from header through line 88 atthe rate of 281,000 lb./hr. to refrigeration zone turbines 89 which aremechanically connected to closed loop refrigeration compressors showngenerally by reference numeral 79. Steam exhausted from these turbinesis also returned through line 92 to feed water recovery system 93.

678,000 lb./hr. of high pressure steam is passed from header 85 throughline 90 to process gas turbine 91 which is mechanically connected toprocess gas compressor 71. A minor portion of this steam is returnedthrough line 92 at the rate of 155,000 lb./hr. to feed water recoverysystem 93. Since high pressure steam produced in the regeneration zone44, quench zone 65, and CO boiler 48 is in excess of the gas compressionenergy requirements of the process and the regenerator air blowerrequirement, 738,000 lb./hr. of high pressure steam is exported by wayof lines 85 and 96 as a product of the process.

A major portion of the steam entering turbin 91 is partially expanded toa medium pressure of about 450 psia. and passed through line 94 at therate of 523,000 lb./hr. to medium pressure steam header 95. It isunderstood that an equivalent amount of steam expanded to the mediumpressure may be exhausted from any of the high pressure steam turbinesaccording to the specific conditions involved.

210,000 lb./hr. of steam from header 95 is further reduced in pressureto about 150 psia. through valve 97 and combined with 100,000 lb./hr. ofsteam from line 98 that is produced at approximately the same pressurein cracker fractionator boiler 99 which removes heat from catalyticallycracked effluent by recirculation of the fractionator bottom contents.The combined stream is then passed through line 63 to thermal pyrolysiszone 35'for use as process diluent stream.

The remaining medium pressure steam is delivere through line 95 and 100to other internal process uses such as pump drives, process heating, andfluidizing steam for the HOC unit.

Thus, the process embodiments of the present invention provide a meansfor the conversion of heavy hydrocarbons to olefins and aromaticcompounds. Whole crude oil and petroleum fractions containingsubstantial amounts of sulfur and metals can be converted to desirableproducts such as ethylene, propylene, benzene, toluene, and the xylenes.The heavy oil cracking concept of the present invention is unique inthat a residuum containing hydrocarbon may be converted and treated to afeedstock suitable for pyrolitic conversion to olefins in the presenceof steam.

The embodiments of the invention are essentially selfsupporting from anenergy balance standpoint. The heavy oil cracking unit provides verylarge quantities of steam which are utilized to provide a major part ofthe gas compression energy requirements of the process. 1n thepetrochemical refinery embodiment of the present invention, all of theinternal gas compression energy and heat requirements of the process arefurnished from the heavy oil cracking unit and the thermal pyrolysisquench zone and substantial quantities of high pressure steam areexported as a product of the process. The feed to the heavy oil crackingunit may be recycled to extinction or a portion of the recycle materialcan be used as plant fuel. The quantity of hydrogen required to saturateand desulfurize the various intermediate fractions produced in thepreferred embodiments is much less than the quantity of hydrogen whichwould be required to support a hydrocracking unit and associatedhydrodesulfurization units.

Obvious variations of process embodiments disclosed in the drawings andthe foregoing descriptions are intended to be included within the scopeof the disclosure and claims.

We claim:

1. A process for the production of olefinically unsaturated hydrocarbonswhich comprises the steps of:

a. introducing a hydrocarbon feedstock comprising petroleum residuuminto the catalytic cracking zone of a heavy oil cracking unit in thepresence of fluidized cracking catalyst at cracking conditions toproduce a catalytically cracked effluent including a cracked naphthafraction;

b. regenerating said fluidized cracking catalyst in the regenerationzone of the heavy oil cracking unit;

c. producing high pressure steam in said regeneration zone by indirectheat exhange;

d. passing the cracked naphtha fraction to a thermal pyrolysis zone andthermally cracking said fraction to produce a thermally cracked effluentcontaining olefinically unsaturated hydrocarbons;

e. expanidng said high pressure steam from step (c) to provide at leastpart of the gas compression energy required for recovery of theolefinically unsaturated hydrocarbons; and

f. recovering olefinically unsaturated hydrocarbons.

2. The process of claim 1 wherein at least a portion of the expandedhigh pressure steam is mixed with the cracked naphtha fraction fed tothe thermal pyrolysis zone.

3. The process of claim 1 wherein the catalytic cracking zone includes atransfer line reactor and the cracking catalyst is a zeolite catalyst.

4. The process of claim 1 wherein the olefinically unsaturatedhydrocarbon contain from two to four carbon atoms.

5. The process of claim 1 wherein the hydrocarbon feedstock is crudepetroleum oil.

6. The process of claim 1 wherein the hydrocarbon feedstock is apertroleum residue containing fraction.

7. The process of claim 1 wherein the hydrocarbon feedstockis anatmospheric residuum boiling above about 600F.

8. An integrated process for the production of olefinically unsaturatedhydrocarbons and aromatic compounds comprising the steps of:

a. introducing hydrocarbon feedstock containing petroleum residuum intothe catalytic cracking zone ofa heavy oil cracking unit in the presenceof fluidized cracking catalyst at cracking conditions to 5 producecatalytically cracked effluent including a cracked naphtha fraction;

b. passing the cracked naphtha fraction to a thermal pryrolysis zone atthermal cracking conditions to produce a thermally cracked effluentcontaining 0 pyrolysis oil, olefinically unsaturated hydrocarbons andaromatic compounds; 0. separating pyrolysis oil from the thermallycracked effluent; d. passing pyrolysis oil to the catalytic crackingzone of the heavy oil cracking unit; and

e. recovering olefinically unsaturated hydrocarbons and aromaticcompounds.

9. An integrated process for the production of olefinically unsaturatedhydrocarbons comprising the steps of:

a. introducing hydrocarbon feedstock containing petroleum residuum intothe catalytic cracking zone ofa heavy oil cracking unit in the presenceof fluidized cracking catalyst to produce a catalytically crackedeffluent including a cracked naphtha fraction;

b. regenerating said fluidized cracking catalyst in the regenerationzone of a heavy oil cracking unit;

c. producing high pressure steam in said regeneration zone by indirectheat exchanage;

d. passing the cracked naphtha fraction to a thermal pyrolysis zone toproduce a thermally cracked effluent containing olefinically unsaturatedhydrocarbons;

e. cooling thermally cracked effluent in a quench zone;

f. producing high pressure steam in the quench zone by indirect heatexchange;

4 g. exapnding high pressure steam from steps (c) and (f) to provide thegas compression energy required for a recovery of olefinicallyunsaturated hydrocarbons; and

h. recovering olefinically unsaturated hydrocarbons.

10. The process of claim 9 wherein a portion of the expanded highpressure steam is passed to the thermal pyrolysis zone as diluent.

11. The rpocess of claim 9 wherein a. flue gas is recovered from theregeneration zone and passed to a carbon monoxide boiler;

b. high pressure steam is produced in the carbon monoxide boiler; and c.high pressure steam is recovered as a product of the process.

V UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.5,862,898 Dated January 28, 1975 Inventor) Harold B. Boyd et a1. V I

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below':

On the Title page, the illustrative drawing should be cancelled and thedrawings shown on the attached sheet should be substituted thereforSigned and sealed this 20th day of May 1975a (SEAL) Attest:

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officerand Trademarks FORM po'wso (10'69) USCOMM-DC scans-P69 U45. GOVERNMENTPRINTING OFFICE: 9 3

' UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No.3,862,898 g Dated January 28, 1975 Inventofls) Harold B. Boycl and.James R. Lambrix Page 5 It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

r In column 1, line 10-, change "porpane" to --propane- In? and change"themal" to ---thermal--. In column 1, line 20, change "minixmize" to-minimize--. In column 1, line 21, change "form" to -from--. In column1, line 25, change "crued" to '-crude--. In column 1,. line 52, change"regenreration" to, --regeneracion--. In column 1, line 67, change "C-C4" to C C In column line 22, change "Wher" to -Where--. In column line39, change "be" to --by-. In column line 52, change "te" to --.the-.

' In column line 28, change "volatitle" to -volatile-.

In column line 14, change "predominantely" to --predominantly-- Incolumn line 23, change "Proudct" to -Product--. In column line 30,change "fro" to --for-. In column line 48, change f" to --F-. In columnline 54, change "pryrolysis" to --pyrolysis--. In column line 30, change"spearated" to --separated--.

In Claim 6, line 2, change "pertroleum" to --petroleum- In Claim 9, line22, change "exapnding" to expanding--. In Claim 11, line 1, change"rpocess" to --process.

1. A PROCESS FOR THE PRODUCTION OF OLEFINICALLY UNSATURATED HYDROCARBONSWHICH COMPRISES THE STEPS OF: A. INTRODUCING A HYDROCARBON FEEDSTOCKCOMPRISING PETROLEUM RESIDUUM INTO THE CATALYTIC CRACKING ZONE OF AHEAVY OIL CRACKING UNIT IN THE PRESENCE OF FLUIDIZED CRACKING CATALYSTAT CRACKING CONDITIONS TO PRODUCE A CATALYTICALLY CRACKED EFFLUENTINCLUDING A CRACKED NAPHTHA FRACTION; B. REGENERATING SAID FLUIDIZEDCRACKING CATALYST IN THE REGENERATION ZONE OF THE HEAVY OIL CRACKINGUNIT; C. PRODUCING HIGH PRESSURE STEAM IN SAID REGENERATION ZONE BYINDIRECT HEAT EXCHANGE; D. PASSING THE CRACKED NAPHTHA FRACTION TO ATHERMAL PYROLYSIS ZONE AND THERMALLY CRACKING SAID FRACTION TO PRODUCE ATHERMALLY CRACKED EFFLUENT CONTAINING OLEFINICALLY UNSATURATEDHYDROCARBONS; E. EXPANDING SAID HIGH PRESSURE STEAN FROM STEP (C) TOPROVIDE AT LEAST PART OF THE GAS COMPRESSION ENERGY REQUIRED FORRECOVERY OF THE OLEFINICALLY UNSATURATED HYDROCARBONS; AND F. RECOVERINGOLEFINICALLY UNSATURATED HYDROCARBONS.
 2. The process of claim 1 whereinat least a portion of the expanded high pressure steam is mixed with thecracked naphtha fraction fed to the thermal pyrolysis zone.
 3. Theprocess of claim 1 wherein the catalytic cracking zone includes atransfer line reactor and the cracking catalyst is a zeolite catalyst.4. The process of claim 1 wherein the olefinically unsaturatedhydrocarbon contain from two to four carbon atoms.
 5. The process ofclaim 1 wherein the hydrocarbon feedstock is crude petroleum oil.
 6. Theprocess of claim 1 wherein tHe hydrocarbon feedstock is a pertroleumresidue containing fraction.
 7. The process of claim 1 wherein thehydrocarbon feedstock is an atmospheric residuum boiling above about600*F.
 8. AN INTEGRATED PROCESS FOR THE PRODUCTION OF OLEFINICALLYUNSATURATED HYDROCARBONS AND AROMATIC COMPOUNDS COMPRISING THE STEPS OF:A. INTRODUCING HYDROCARBON FEEDSTOCK CONTAINING PETROLEUM RESIDUUM INTOTHE CATALYTIC CRACKING ZONE OF A HEAVY OIL CRACKING UNIT IN THE PRESENCEOF FLUIDIZED CRACKING CATALYST AT CRACKING CONDITIONS TO PRODUCECATALYTICALLY CRACKED EFFLUENT INCLUDING A CRACKED NAPHTHA FRACTION; B.PASSING THE CRACKED NAPHTHA FRACTION TO A THERMAL PRYROLYSIS ZONE ATTHERMAL CRACKING CONDITIONS TO PRODUCE A THERMALLY CRACKED EFFLUENTCONTAINING PYROLYSIS OIL, OLEFINICALLY UNSATURATED HYDROCARBONS ANDAROMATIC COMPOUNDS; C. SEPARTING PYROLYSIS OIL FROM THE THERMALLYCRACKED EFFLUENT; D. PASSING PYROLYSIS OIL TO THE CATALYTIC CRACKINGZONE OF THE HEAVY OIL CRACKING UNIT; AND E. RECOVERING OLEFINICALLYUNSATURATED HYDROCARBONS AND AROMATIC COMPOUNDS.
 9. An integratedprocess for the production of olefinically unsaturated hydrocarbonscomprising the steps of: a. introducing hydrocarbon feedstock containingpetroleum residuum into the catalytic cracking zone of a heavy oilcracking unit in the presence of fluidized cracking catalyst to producea catalytically cracked effluent including a cracked naphtha fraction;b. regenerating said fluidized cracking catalyst in the regenerationzone of a heavy oil cracking unit; c. producing high pressure steam insaid regeneration zone by indirect heat exchanage; d. passing thecracked naphtha fraction to a thermal pyrolysis zone to produce athermally cracked effluent containing olefinically unsaturatedhydrocarbons; e. cooling thermally cracked effluent in a quench zone; f.producing high pressure steam in the quench zone by indirect heatexchange; g. exapnding high pressure steam from steps (c) and (f) toprovide the gas compression energy required for a recovery ofolefinically unsaturated hydrocarbons; and h. recovering olefinicallyunsaturated hydrocarbons.
 10. The process of claim 9 wherein a portionof the expanded high pressure steam is passed to the thermal pyrolysiszone as diluent.
 11. The rpocess of claim 9 wherein a. flue gas isrecovered from the regeneration zone and passed to a carbon monoxideboiler; b. high pressure steam is produced in the carbon monoxideboiler; and c. high pressure steam is recovered as a product of theprocess.